[Premium-Rx] Faraday Shield.....To Be, or Not to Be?? Need advice, please!

[Gary Geissinger]

A couple words about building a screen room.
 
1.  Believe it or not, you can shield a room with aluminum foil.  It's
best to use a 50% overlap and fold all the corners just right.  This is
described in several NSA documents.  Done correctly, you can get at most
60 dB of shielding effectiveness this way.  You can't get more, because
you would need mu-metal (or other magnetic material), etc for the mag
shielding required.  There is a section of this document at:
http://cryptome.quintessenz.at/mirror/emp12.htm.  If you want to trade
off other shielding materials, there is a "Perry-Graf" "shielding design
guide available from Instrument Specialties Corp (717-424-8510).
 
One additional comment.  I have seen this done almost invisibly.  You
sheet rock the room normally, with a plywood floor, but of course use
EMI filters on lights, power connections, phone etc.  Then you apply the
aluminum foil as described above.  Then, you apply another layer of
sheet rock over the aluminum foil.  If done carefully, with aluminum
foil, or something (screen?) under the tile (on top of the plywood
floor), with a door as described below, you can do this so that only a
trained eye can spot it.
 
2.  For the door, a steel fire-proof door with matching steel door-jam
and kick plate work great.  Use the lighest fingerstock you can find on
the seams.  Some folks just use braid to connect the door to the jam,
but I can't believe that is adequate.  If you have room, you don't need
a door at all.  Just make a "serpentine" path to walk through and line
the pathway with RF absorber.   Frankly, for home use, the steel fire
doors make more sense.
 
Ed, feel free to email me directly on this.  I have fought this problem
several times...I think I won!
 
Gary WA0SPM
ggeissinger at digitalglobe.com
 
 
 
 

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	-----Original Message-----
	From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Aidehua at aol.com
	Sent: Wednesday, January 05, 2005 3:00 PM
	To: premium-rx at ml.skirrow.org
	Subject: [Premium-Rx] Faraday Shield.....To Be, or Not to Be??
Need advice,please!
	
	
	
	I am building a radio room for my Premium-Rxs and transceivers
from scratch, and was wondering the pro-and-cons of constructing a
totally shielded (screen room) approach, with bypassed 120, and multiple
short grounding paths to the earth (all bonded, of course!).  In other
words, a Faraday shielded room for ultraquiet conditions and maximum RF
suppression.  I am turning to the experts on this List, as I'd like the
appropriate guidance.  Your input is appreciated!  Happy New Year!!
	 
	73,
	Ed NI6S  
	

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